45°38'N-13°47'E
Deity
Is ever an issue in the game? I see that happiness is a great limiting factor but health?
So an other idea, similar to unhappiness from distance and number of cities mechanism: What if cities received 0.1 from every city it is connected to (own or foreign doesn't matter)?
I think this would be something that also represents the spread of diseases (realism) and improve game play, as you should reconsider Open Borders / Right of Passage.
I have the opposite feeling
Never had an issue with happiness but unhealthiness is a constant pain in the ... around industrial at least.